1. Field of the Invention
The present invention relates to an ink jet recording apparatus wherein ink is discharged from a recording means to a recording material for recording.
2. Related Background Art
Recording apparatuses having functions of printers, copying machines, facsimile equipment, etc. or recording apparatuses used as output equipment for composite electronic equipment including computers and word processors and workstations are constructed so as to record images on a recording material (recording medium) such as paper, plastic sheets, etc. on the basis of image information. Said recording apparatuses are divided into ink jet type, wire dot type, thermal type, laser beam type, etc. according to recording systems.
In serial type recording apparatuses employing a serial scan system wherein main scanning is performed in a direction across the direction of feeding of a recording material (direction of sub-scanning), after setting the recording material in a predetermined recording position, an image is recorded (main scanned) by a recording means mounted on a carriage which moves along the recording material; after recording for one line has been completed, a paper conveyance or feed of a predetermined amount (pitch feed) is performed; then, an image for a next line is recorded (main scanned) on the recording material, the feeding of which is again halted; and such recording and feeding operations are repeated for recording on the entire recording material. Meanwhile, in line type recording apparatuses wherein recording is made only by sub-scanning in the direction of feeding of a recording material, after setting the recording material in a predetermined position and recording one line at a time, a paper feed of a predetermined amount (pitch feed) is performed, and again, for a next line is recorded at one time; and such recording and feeding operations are repeated for recording on the entire recording material.
Among recording apparatuses described above, ink jet type recording apparatuses (ink jet recording apparatuses) record by discharging ink from a recording means (recording head) to a recording material and have such features that a compact recording means is easy to implement, high-definition images can be recorded at a high speed, recording can be made on plain paper without requiring special treatment thereon, a running cost is cheap, noise is less because it is of non-impact type, and it is easy to record color images by using multicolor ink. In particular, line type recording apparatuses, which use a line type recording means with many discharge ports arranged across the width of paper, can implement recording at higher speeds.
Especially, as for ink jet type recording means (recording heads) which utilize thermal energy for discharging ink, it is easy to manufacture models having highly dense liquid path arrangements (discharge ports/arrangements) by forming electrothermal conversion bodies, electrodes, liquid path walls, top plates, etc. in the form of a film on a board through semiconductor manufacturing processes such as etching, vapor deposition, sputtering, etc.; thus, the recording means can be made more compact. On the other hand, there are various demands on recording materials; in recent years, it has been required to use thin paper and processed paper (paper with punched holes for filing, paper with perforations, paper in nonstandard shape, etc.) in addition to ordinary recording materials including paper and thin resin sheets (for use with OHP, etc.).
In ink jet recording apparatuses described above, if foreign matter such as paper dust, other dust or the like adheres to an ink discharge portion, or if ink in a discharge port portion increases in viscosity or gets stuck due to drying, discharge problems (including nondischarging) may result; to prevent such problems, employed is the method of closing the ink discharge portion with a cap when recording is not effected. The cap is usually formed from rubber-like elastic material.
Ink jet recording apparatuses described above are constructed so as to automatically execute various sequences for stabilizing discharge from a recording head; if recording apparatus power is turned off by a user inadvertently or for any other causes, closing an ink discharge portion with a cap (capping) has failed in some cases. If a recording apparatus is transported or left unused for a long period of time in the state that closing an ink discharge portion with a cap (capping) is not securely done, it is more likely that discharge problems will occur due to ink leakage from a discharge port or ink sticking or an increase in ink viscosity within a discharge port in transit, and also that vibrations or the like will cause air to enter a meniscus portion. Hence, for preventing incomplete capping, conventional ink jet recording apparatuses not only inhibit power from being turned off during recording but employ the method of turning power off after waiting for a time required for secure capping, or the method of turning power off on detecting the completion of capping by means of a mechanical operating sound. In addition, in recording apparatuses having a power off sequence, a series of sequences is always executed after a recording apparatus power has been turned off, and hence, a substantially long waiting time has been needed, and a power cord has been unable to be disconnected from an outlet during executing the series of sequences.
However, in aforementioned ink jet recording apparatuses, it is difficult to judge under a black box state whether a recording head is in a capped state, and thus, a user has been required to wait for a longer time than needed. Also, when a recording apparatus is in an on-line state, recording will start at an indefinite time under a command for recording from a host such as a personal computer or the like, and hence, a recording apparatus system is so constructed that a cap is left open for up to a predetermined period of time for quick response to a next command for recording. As a result, it is very difficult to judge whether a cap is open or closed, and consequently, it has been likely to turn power off with the cap being left open.
Also, even when a recording apparatus is in an off-line state, the operation of the recording apparatus itself may be executed for stable discharge from discharge ports; even in such a case, it is difficult to judge the state of a cap, and consequently, it has been likely to turn power off with the cap being left open. In addition, even for recording apparatuses having a power off sequence, there has been the problem to be solved that a waiting time after turning power off is long, and hence, an apparatus cost increases, and an extra space is needed.
In addition, in recent years, portable type ink jet recording apparatuses have been developed for easy carrying. For such portable type ink jet recording apparatuses, the necessity of capping ink discharge ports is much greater because of a diversity of handling the apparatuses when the apparatuses are carried. However, the above-noted power off sequence requires portable type ink jet recording apparatuses to have a built-in backup power source, and hence, there has been a difficulty in reducing the size and weight of the apparatuses.